Problem A. 649. (September 2015)
A. 649. A convex polyhedron has only quadrilateral faces. Show that it is possible to split every face into two triangles by drawing one of its diagonals in such a way that at each vertex of the polyhedron, an even number of triangles meet.
Proposed by: János Nagy, Budapest
Deadline expired on 12 October 2015.
|5 students sent a solution.|
|5 points:||Bodnár Levente, Lajkó Kálmán.|
|1 point:||1 student.|
|0 point:||2 students.|